Springfield daily republic. [volume] (Springfield, O. [Ohio]) 1887-1888, 1887-03-04
PHOTOTYPIC WORK.
SOMETHING ABOUT The VARIOUS
PROCESSES NOW EMPLOYED.

SOMt HING ABOUT HE VARIOUS
PROCESSES NOW EMPLOYED.
The Methods of GoupiI, ia Paris-pnirk-
ness Of American Proresse--The Ac-
tiou of Light on >.nsiiiscd Geiatine.
Photogravure.
The most common forms nf reproductive
art nowaday, are those based on photog-
. raphy. aud il may not bc generally known
/ that the most extensive concern in the
country that is devoted to this kind of
work is housed in Brooklyn. The COM
1 pany who controls these works and give
, employment to Il considerable number Of
! operatives. some of whom are to he re
gGrdrd rs artists rather than mechanics
| for into the finishing and printing Of the
plates taste rs well as skill must enter.
The house Of Goupil, in Paris, has until
recent Years enjoyed almost u monopoly
of photograNurc, aud its work has celeb
rity for strength and Cicarness The
Guupil process is u secret. hut it is evi-
dent from The length of time taken to
prepare Il plate, and from the appearance
of suudry lines and markings that would
not commonly show in solar print, that
hand work is nearly as important "a fac
tor rs chemical evolution. The company
here in Brooklyn finishes plate in as
many hours as days are taken by the
GOupil firm. and the results are in many
instances surprising. Advances in The
art are still Ia be made. but there is
broad foundation towork upward from.
There are dozens Of names for what is
substantially the same prOcess-the photo
type, phntoprirt, moSstype. albcrtype,
artotypc. iiChtdruk, heliotype, carbon
print, autoglyph. Ives process, Meisen-
bach process, photo lithograph. photo
caustic print photo gelatine print. photo
engraving. zinc etching and photogra-
Vure The action Of light on sensitized
geiatine ur ether material is the occasion
of all these forms. Gclatine is made sen
sitiVc hy treatment with bichromate of
potash. which likewise renders il insol-
able ly water, and in this condition it
win take" grease when that is applied,
but when Il goiatine sheet is placed under
Il Photographic negative the effect of light
striking through the glass is To close the
pores Of the gelatine and harden it, and
where light does not net the Celatine he
comes soft and absorbent. After the
sheet has received the impress from the
negative a greasy ink will adhere to the
hard portions, while the sponge areas,
being kept moist with water, refuse H.
You apply your ink, lay piece of paper
on il, stamp it, the ink comes off on the
paper and there is your picturc-a hello
type, iii commercial phrase.
APPLIED TO STONE PRINTING
This process is much the same as lith-
ography. but the photographic stone holds
grease only where there are decided lines,
while gciatiue receives the impress OF :.
hundred gradations Of light and shade.
Photography is applied to stone printing
where anything is TO be repre- sented by
clean masses If black and white. and il is
therefore useful for copying maps, plans,
tracingS, ink drawings, designs, miniature
calendars, papers and catalogues. line en-
cravings, autograph letters. and SO on.
In that case paper coated with aelarine is
printed on by a negative, as in the cases
OF an ordinary photograph, and the grease
taking lines are transferred bodily Ia the
stone. When the ink lines are transferred
tn Ziuc instead Of stone and the exposed
portions of the metal are eaten down hy
acid. leaving the lines in relief. a plate i
made that j. similar To stereotype, and
this form il cnmmuuly used for cheap il
lus,ra.ionS in daily papers. \ plaster
east may lie taken from gelatne i'm
press after The lines have set, and from
this may De made h metal plate that Will
print what are called photo encravings.
For phot0gfavurc bichromatized geIa-
tine is mixed with sand or emery dust. the
picture Is thrown GA it from "a negative.
the grease taking lines harden. the licht
portions are swollen with water and Il
copper shell is deposited on it rs an electro !
type. The sand gives grain to the sur
face and holds the ink where it is drsir- |
able to imFart a half tint. In the hands |
of skilllul printer Il proof photOgravrre |
can he made alnoSt rs strong as an etch- |
ing. as it is easy ia wipe ont the high |
lights until they are represented by he |
actual whitcness of the paper that re-
ceivcs tine print while tones and masses |
of shadow are obtainable by leaving films ,
Of ink "f less or greater density on the /
metal surfacc.-Brooklyn Eagle.